IN-VIVO SAMPLE UPTAKE AND ONLINE MEASUREMENTS OF COBALT IN WHOLE-BLOOD BY MICROWAVE-ASSISTED MINERALIZATION AND FLOW-INJECTION ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY - PUBLISHED IN CELEBRATION OF THE 10TH ANNIVERSARY

An on-line automated microwave-assisted mineralization and Bow injecti on system was developed for the determination of cobalt in whole blood with in vivo sample uptake by electrothermal atomic absorption spectr ometry, The samples were drawn and at the same time pumped directly fr om the vein of a patient's forearm to a timed injector, which is autom atically controlled to inject the sample-nitric acid-anticoagulant mix ture into the carrier stream. Volumes (20 mu l) of the mineralized sam ples, collected in a capillary of a sampling arm assembly, were introd uced by means of positive displacement with air through a time-based s olenoid injector (TBSI) into the graphite tube atomizer, The spectrome ter autosampler, used for the introduction of 10 mu l of the chemical modifier, magnesium nitrate, and the furnace programme were re-program med to synchronize with the operation of the flow system, The linear r ange was from 0 to 50 mu g l(-1) of cobalt, achieving a precision of 2 .6 and 3.1% for 10 replicate analyses of a 5 mu g l(-1) cobalt standar d solution and a certified sample, respectively, with a detection limi t of 0.3 mu g l(-1). The agreement between the observed and certified values obtained from Seronorm Whole Blood Standard Reference Materials was good, The results obtained by using an in-batch procedure were fo und to linearly increase by 5% during the time interval; between sampl e collection and analysis for the first hour; after this time the resu lts for cobalt levelled off and mere then in close agreement with thos e obtained by the on-line procedure proposed here.